setenv.add-response-headerAdds a header to the HTTP response sent to the client:

setenv.add-response-header = (
"Content-Encoding" => "gzip"
)

setenv.add-request-headerAdds a header to the HTTP request that was received from the client:

setenv.add-request-header = (
"X-Proxy" => server.name
)

setenv.set-request-header (since 1.4.46)setenv.set-response-header (since 1.4.46)setenv.set-environment (since 1.4.46)These directives set the given values, rather than appending the given values to the headers or environment. These directives take precedence over the setenv.add-* counterparts. Set a blank value for request or response header to remove the header.